So, I was working with Clojure and… well… it seemed to be the worst combination of slow start-up and slow compilation… and it's supposed to be a dynamic language. So, I pinged the very nice people in the Clojure community and they pointed me in the right direction.

Basically, everything you do in Clojure, you do in the REPL. The REPL is a live coding environment.

Test First

I had been writing code and tests and then checking on my tests with: lein test But that was taking way too long (20 seconds per cycle on my MacBook Pro).

The magic is when we :reload-all, then all the dependencies for the package being used are re-loaded as well. But in the REPL, the reload process takes no measurable time. This makes the cycle very, very fast. Change code, switch to the REPL, up-arrow twice, hit return, up-arrow twice, hit return and voila… your new test results.